1a(1): a condition of being hot : warmthsnow melting in the heat of the sun

(2): a marked or notable degree of hotness
The heat was intense.

b: pathological excessive bodily temperature
the heat of the fever

c: a hot place or situation
get out of the heat

d(1): a period of heat
an unbroken heat

(2): a single complete operation of making something warm or hotalso: the quantity of material so heated

e(1)physics: added energy that causes substances to rise in temperature, fuse, evaporate, expand, or undergo any of various other related changes, that flows to a body by contact with or radiation from bodies at higher temperatures, and that can be produced in a body (as by compression)

(2)physics: the energy associated with the random motions of the molecules, atoms, or smaller structural units of which matter is composed

f: appearance, condition, or color of something as indicating its temperature
when the rod is at the proper welding heat

Examples of heat in a Sentence

Verb

I heated the vegetables in the microwave.
They heat their house with a wood stove.

Noun

The sun's heat melted the snow.
the intense heat of a fire
She applied heat to the sore muscles in her leg.
a period of high heat and humidity
The crops were damaged by drought and extreme heat.
Cook the milk over low heat.
Remove the pan from the heat.

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'heat.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Medical Definition of heat

1a: the state of a body or of matter that is perceived as opposed to cold and is characterized by elevation of temperature : a condition of being hotespecially: a marked or notable degree of this state : high temperature

b(1): a feverish state of the body : pathological excessive bodily temperature (as from inflammation)
knew the throbbing heat of an abscessthe heat of the fever

(2): a warm flushed condition of the body (as after exercise) : a sensation produced by or like that produced by contact with or approach to heated matter

c(1): added energy that causes substances to rise in temperature, fuse, evaporate, expand, or undergo any of various other related changes, that flows to a body by contact with or radiation from bodies at higher temperatures, and that can be produced in a body (as by compression)

(2): the energy associated with the random motions of the molecules, atoms, or smaller structural units of which matter is composed